Photoluminescence properties of Tb3+ and Eu3+ ions co-doped SrMg2La2W2O12 phosphors for solid state lighting applications

In this paper, we report a series of Tb3+ and Eu3+ activated SrMg2La2W2O12 phosphors synthesized by the solid state reaction method. The structural and photoluminescence properties have been characterized and analyzed by X-ray diffraction, Fourier transform infrared spectroscopy, photoluminescence and decay measurements. X-ray diffraction pattern confirms that the SrMg2La2W2O12 powders were well indexed to orthorhombic structure (JCPDS card No. 35-0259). The excitation spectra monitored at 547 and 617 nm consist of a broad band in the region 250-370 nm pertaining to O -> W ligand to metal charge transfer transition and several narrow bands related to Tb3+ and Eu3+ ions absorptions, respectively. The emission spectra of singly Tb3+ and Eu3+ doped SrMg2La2W2O12 phosphors consist of narrow bands from 4f-4f emission transitions of D-5(4) and D-5(0) excited levels to several lower lying levels of Tb3+ and Eu3+ ions, respectively. The emission color of phosphors doped with Tb3+ and Eu3+ ions has been changed by varying concentrations and excitation wavelengths to obtain white light emission. The Commission Internationale de L'eclairage (CIE) chromaticity coordinates and correlated color temperatures (T-cct) show that the SrMg2La2W2O12:TbEu phosphors can be tuned to exhibit white light emission ranging from 450 to 750 nm, when they are excited by ultraviolet (UV) light. (C) 2013 Elsevier B.V. All rights reserved.